This invention relates to medical devices for drawing blood samples, and more particularly to a safety multiple sample rear adapter assembly that makes it easier to draw blood samples from patients, and at the same time, provides substantial protection against needlesticks.
Drawing blood samples from patients is often a difficult task especially if a patient has small veins as is frequently the case with children, small women or the elderly. It is not unusual for a patient with small veins to be stuck more than once using standard blood collection needles before the needle is positioned properly in the vein to draw the blood sample. This problem can cause the patient physical distress and considerable anxiety. Under such conditions, the medical staff is also subjected to increased stress because of the patient's reaction to the difficulty of the procedure.
Winged needle devices, which give the phlebotomist greater control of the venipuncture procedure, can be helpful in solving the problem of taking blood samples from patients with small veins. The smaller winged needle device, because of its reduced size, allows the medical staff to position the needle more accurately, which significantly reduces the number of times a patient must be stuck with the needle to produce satisfactory blood sampling. However, standard winged needle devices do not have means for accepting blood collection vacuum tubes which provide negative pressure for drawing blood and in which the drawn blood is collected.
In order to permit the use of a winged needle device with a blood collection vacuum tube, it was proposed in U.S. Pat. No. 4,140,108 issued to Nugent to provide a blood collection assembly with a rear needle adapter for use in taking blood samples. The blood collection assembly of Nugent is comprised of several parts, including a rear needle adapter, and flexible tubing with hubs and needles on each end (one venipuncture needle and one rear needle for puncturing a stopper on a vacuum tube). The venipuncture needle is in open communication with the tubing and is held in the tubing by attachment to the hub. The rear needle is attached to the flexible tubing via the rear hub. The rear hub has external male helical threads which permit it to be screwed to and unscrewed from the forward hub portion of a standard rear blood tube holder which has reciprocating internal female helical threads. The standard rear blood tube holder also includes a receiving cylinder which is open at one end for receiving blood collection vacuum tubes.
In using the device disclosed by the Nugent patent, the rear needle attached to the male threaded hub is placed in the forward hub portion of a standard rear blood tube holder, and the rear hub on the flexible tubing is mated with the forward hub portion of a standard rear blood tube holder by screwing the two together The assembly is then ready to have standard blood collection vacuum tube(s) inserted in the receiving cylinder of the rear blood tube holder, such that the rear needle will puncture the stopper of the blood collection vacuum tube and blood will be collected. When the blood sampling procedure is finished, the venipuncture needle is removed from the patient's vein, and the rear needle is removed from the standard rear blood tube holder by unscrewing the hub holding the rear needle. The rear blood tube holder is then saved for subsequent uses. However, upon disassembly, the venipuncture and rear needles are contaminated and left completely exposed increasing the possibility of unwanted needlesticks occurring.